Input for user choose his Collatz sequence

[hugofolloni]

Describe your change:

Now the user can tell the algorithm what number he wants to run on the Collatz Sequence.

• [ ] Add an algorithm?
• [x] Fix a bug or typo in an existing algorithm?
• [ ] Documentation change?

Checklist:

• [x] I have read CONTRIBUTING.md.
• [x] This pull request is all my own work -- I have not plagiarized.
• [x] I know that pull requests will not be merged if they fail the automated tests.
• [x] This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• [x] All new Python files are placed inside an existing directory.
• [x] All filenames are in all lowercase characters with no spaces or dashes.
• [x] All functions and variable names follow Python naming conventions.
• [x] All function parameters and return values are annotated with Python type hints.
• [x] All functions have doctests that pass the automated testing.
• [x] All new algorithms have a URL in its comments that points to Wikipedia or other similar explanation.
• [x] If this pull request resolves one or more open issues then the commit message contains Fixes: #{$ISSUE_NO}.

[stale[bot]]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[tianyizheng02]

@cclauss This is a fairly simple addition and should be fine to merge, as long as it passes our current checks since this is a pretty old PR

[tianyizheng02]

Closing in favor of #8911 to fix merge conflicts, thanks for your contribution @hugofolloni!